High-Fructose Corn Syrup and Mercury

What you need to know about high-fructose corn syrup and mercury.

Two studies released January 26, 2009 reveal that high-fructose corn syrup (HFCS), an ingredient common in processed foods, may contain mercury. One of the studies, published in the journal Environmental Health, found that almost half of 20 commercial HFCS samples tested contained mercury. The second report revealed that of 55 foods tested—including yogurts, salad dressings and condiments containing HFCS—about one-third had detectable mercury levels.

EatingWell talked through the findings with an author of both studies, David Wallinga, M.D., food and health director of the Institute for Agriculture and Trade Policy. Here’s what you should know:

1. Mercury in fish has been linked with thwarted brain development in babies. Mercury, a heavy metal, occurs naturally in the environment and is released into the air through industrial pollution. It can accumulate in streams and oceans where certain microorganisms can turn it into methylmercury, a highly toxic form of mercury that accumulates in fish and shellfish. (Generally, fish that are higher on the food chain and live longer contain more mercury.) Methylmercury is known to have toxic effects on the nervous system.

While there’s no conclusive evidence that, at levels found in fish, mercury is a danger to adults, it is a concern for the very young, whose nervous systems are still developing. Thus, the Food and Drug Administration and the Environmental Protection Agency recommend that women of childbearing age and young children avoid certain types of fish that contain high levels of mercury (shark, swordfish, king mackerel and tile fish) and limit other seafood to 12 ounces per week.

2. Eating foods containing HFCS may put you at additional risk for mercury exposure. "Up till now, just about everyone thought that exposure to mercury [through food] came from fish and seafood," says Wallinga. "The Environmental Health study finds detectable mercury in about half of the HFCS-foods tested. If that were to hold true across the high-fructose corn syrup industry then the possible exposures could be pretty significant."

3. Not all high-fructose corn syrup contains mercury. Mercury isn’t inherent in HFCS. The sweetener gets contaminated when it’s made with caustic soda that has been produced by manufacturing plants that use mercury in their manufacturing processes. These mercury-dependent processes are unnecessary and outdated; in fact, 90 percent of the U.S. plants that make caustic soda have upgraded to a mercury-free technology. "The main point is we don’t need to make HFCS in ways that contaminate it with mercury," says Wallinga. "There are ways to make high-fructose corn syrup using caustic sodas made from these cleaner technologies."

4. It’s impossible to tell what products are most likely contaminated. And, until now, the companies that made the foods found to contain mercury may not have even considered asking how the HFCS they put in their products was made. (The companies that make the HFCS itself do know whether mercury is used to make the caustic soda they source.) "In the short term, the consumer is in the dark about where their HFCS-laden foods and beverages come from," says Wallinga. "I think a reasonable approach would be for people to elect to avoid foods with [HFCS] until they know more about the products they want to buy and eat."

5. You can help reduce mercury in food ingredients, such as HFCS. Write to your legislators, suggests Wallinga. "I would say this: 'Pass legislation that, beginning now, will phase out the use of mercury in chlor-alkali plants [which produce caustic soda]. And begin now to monitor food-grade products, including caustic soda, from those plants to make sure that they’re free of mercury.' "